Doors and their suspension from jams predate written history. Despite humanity's long experience with doors, jams, and hinges, these common items have been the subject of much improvement and invention. Compound and "invisible" door hinges and continous-hinge arrangements have been suggested in U.S. Pat. Nos.: 283,416; 414,461; 509,702; 993,227; 1,220,084; 2,067,042; 2,206,739; 2,219,358; 3,016,261; 3,092,870; and 3,374,499.
The relatively recent U.S. Pat. No. 3,973,289 to Yulkowski discloses a commercially-employed hinge that is hidden and allows for swing of up to 180 degrees. This hinge, and others like it, however, suffer from the drawback that they require a large spacing or gap between the vertical side edge of the door and the jam. It also provides a double hinge arrangement, wherein the angles of pivot of the individual hinges are not coordinated with each other. That is, one can pivot a large angle while the other doesn't pivot at all.
Architects and others concerned with the appearance of doors and jams generally prefer that there exist little or no visible gap between the closed door and the jam and that the hinges be "invisible"; that is, hidden from sight when the door is closed. Further, it is, of course, desirable that the door hinge and jam perform their function of closing the opening with strength and operate smoothly and reliably and consistently in the same manner.